Eraser.



T. W. HANRATH.

ERASER. APPLICATION FILED JAN. 2, 1914.

Patented Nov. 3, 1914.

KQPX Q5235 THE NORRIS PETERS ca, PHOTO-LITHO. WASHINGION. D. C

THEODORE w. VI-IANRATI-I, or oHIcnso, rumors.

ERASER.

Specification of Letters Patent.

Patented Nov. 3,1914.

Application filed January 2, 1914. SerialNo. 809,878.

T all whom it may concern Be it known that I, THEODORE W HAN- nirrrr, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Erasers,of which the following is a specification.

My invention relates to erasers especially blackboard erasers and the objects of the invention are first, to produce an eraser having four acting surfaces, second, to produce an eraser composed chiefly of felt and yet having great rigidity so as to maintain its shape during actual use uponthe board, th rd, to produce a durable and eflicient erascrwhich is simple to manufacture and can be produced at low cost, fourth, to provide a simple, quick and efiicient method of constructing an eraser having the characteristics mentioned.

I obtain my objects in the manner illustrated in the accompanying drawings in which Figure 1 is a perspective view of an eraser embodying my invention. Fig. 2 is a longitudinal section taken on the line 22, Fig. 1. Fig. is a longitudinal section taken on the line 33, Fig. 2. Fig. 4 is an end view of the eraser. Fig. 5 is a cross sectional view taken on the line 55, Fig. 2. Fig. 6 is a perspective of the end of the mandrel which forms the core of the eraser.

Similar numerals refer to similar parts throughout the several views.

The mandrel l which forms the core of the eraser is composed of wood or eouivalent material which is light in weight and at the same time rigid or substantially so. While the cross section of the mandrel may be varied, I prefer for ordinary erasers to employ a mandrel approximately a quarter of an inch thick and one inch wide. Its length ordinarily is about six inches, and at the end it has notches 1 best shown in Fig. 6. Over this mandrel I pass a number of laminations 2 these being preferably of felt about two inches square and approximately a quarter of an inch thick. These laminations occupy the entire length of the mandrel and are punched at the center with holes 1 of substantially the same cross sectional dimensions as the mandrel so that when the laminations are in position upon the mandrel they will form a rigid body in'the sense that the eraser as a whole will resist. torsional or warping strains, the only yield being that due to the softness of the felt itself. In other words, my eraser when completed firmly maintains its general configuration although the felt, being soft, makes the eraser soft to the touch and enables it to perform its function of cleaning the surfaces of the board.

At each end I place a lamination 3 which is the same as the laminations 2 except that it is imperforate. These end laminations lie against the ends of the mandrel and not only impartafinished appearance to the device but also protect the blackboard from contact with the h ardmandrel.

In addition to the center hole l above mentioned, the internal laminations 2 are punched with a set of perforations 1 which according to the present design are four in number and are symmetrically arranged in pairs on opposite sides of the mandrel in alinement with the end notches 1 thereof. Theseperforations 1 are located far enough away from the center hole 1 to afford plenty of material between the perforation and the hole for withstanding the binding action'of the cords a by which the parts are held assembled. In the best construction the cords are arranged in pairs, onepassing one way and the companion cord passing the'opposite way through any given perforation The most desirable method of manufacture is this:

After the internal laminations 2 are punched, glued and properly assembled upon the mandrel, one of the cords 4 is, by the aid of a needle passed part way through the thickness-of one of the end laminations 3 as shown for example at the right end of Fig. 2. The two ends of the cord are then passed through the apertures 1 on opposite sides of the mandrel and the ends are brought out at the far end of the device. Next, the same method is pursued with the companion cord except that it is passed through the body of the opposite end lamination and the ends of the second cord are led in the opposite direction but through the sameperforations which contain the first mentioned cord. In other words, two companion cords pass through the perforations in opposite directions and are looped through the body of the laminations at the opposite ends of the eraser. This threading of the cord is repeated for each pair of perforations. This leaves two loose ends of each cord sticking not loopedinto the end lamination, that is c passed into the body of the lamination but brought out at the same surface at which it passes in, and it should be brought out as near as possible to the point of exit of the loose end of the same string. This act is repeated for each of the cords and after they are all in place they are drawn tight and knotted, the knots thus occurring between the end lamination and the one adjacent to it, as best shown in Fig. 2. When the knots are tied it will be found that the parts are all securely held together and yet the cording, or stitching, if it may be so termed, is blind, no evidence of the presence of the cords being apparent.

As a result of my invention an eraser is produced which has four acting surfaces and which is rigid so that it will stand up to its work while it is at the same time soft to the touch and is noiseless, for no wood or other hard material can comeinto contact with the board, nor with the floor in case the eraser should be dropped.

Those familiar with the use of blackboard erasers especially in the primary schools where the attention of pupils is easily distracted will appreciate the desirability of an eraser which is rigid so that it will firmly hold itself to the work but which if dropped will, practically speaking, make no audible sound.

Having thus described my invention, What I claim as new and desire to secure by Letters Patent is v 1. A blackboard eraser consisting of a plurality of laminations of erasive material, each presenting their edges for action upon the board, a one piece rigid mandrel inclosed within said laminations, the end laminations being imperforate and lying adjacent to the mandrel, said mandrel being comparatively flat, and a plurality of parallel cords longitudinally encircling said mandrel at different points widthwise thereof, said cords passing through the endlamination for holding all of the parts in proper relation.

2. A blackboard eraser composed of a plurality of felt laminations of rectangular outline each presenting four cut edges for action upon the board, a rigid mandrel passing through said laminations and inclosed therein, imperforate end laminations similar to the others and located in contact with the ends of the mandrel, and filaments embedded within the laminations and longitudinally encircling the mandrel at a slight distance therefrom for holding the parts together.

In witness whereof, I have hereunto subscribed my name in the presence of two witnesses.

THEODORE W. HANRATH. Witnesses HOWARD M. Cox, KATHRYN S. READY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

